It is known from EP 1 211 382 A2 that flutter may occur in compressors. To reduce this, EP 1 211 382 A2 proposes rotor blades having different natural frequencies.
In addition to such structural mistuning, it is further known from US 2010/0247310 A1 to mistune the rotor blades by providing them with different thicknesses on the pressure side.
Both publications deal with normal flow through the compressor; i.e., a flow towards the airfoil leading edges. However, during the so-called “pumping”, the direction of flow may briefly reverse. Flutter may occur here as well.